1. Field of the Invention
This invention relates to a pressure compensation device, a preheater, and an improved regeneration cell for an air conditioning system that includes a purge vessel.
2. Description of the Prior Art
Efficient operation of chiller condensers and evaporators requires a purge device therebetween for the removal of contaminants such as acid, moisture, noncondensibles, and other debris from the refrigerant. If contaminants could be completely separated from the refrigerant, such contaminants could be purged from the system into the atmosphere without purging any refrigerant into the atmosphere. However, total separation is not possible and even the best purge devices will purge at least some refrigerant into the atmosphere. U.S. Pat. No. 5,309,729 by the present inventor discloses the most efficient purge device heretofore known; that disclosure is hereby expressly incorporated hereinto by reference.
As a purge device operates, clean, condensed refrigerant accumulates therewithin. The device is preferably mounted atop a condenser barrel of a chiller so that said clean, liquid refrigerant may flow from an upstanding overflow pipe that projects upwardly from a bottom wall of the purge device into the evaporator barrel of the chiller. However, where space limitations do not permit such mounting, the purge device must be placed at a lower level and a pump must be employed to return the clean refrigerant to the evaporator barrel.
Both of these expedients for returning clean refrigerant to the evaporator barrel have drawbacks. For example, in the condenser-evaporator system, a float is employed to open and close a valve between the overflow pipe and the evaporator barrel because the liquid level must be maintained above the opening of the overflow pipe and at a predetermined level below the coils of the purge vessel. In the pump-reliant system, a float must be employed to activate and deactivate the pump to maintain preferred liquid levels within the purge vessel.
Mechanical floats are notorious for jamming and rapid deterioration in the environment of a purge vessel. Less maintenance-intensive substitutes are available, including moisture sensors, electric eye devices, and the like, but these alternatives increase the expense of the purge vessel and are themselves subject to maintenance problems.
What is needed, then is an improved means for maintaining a desired liquid refrigerant level within a purge vessel. The improved means should not require mounting atop a condenser barrel and it should not include floats, pump or other parts that require frequent maintenance and which are subject to failure.
Separation of refrigerant and contaminants requires the highest possible differential in temperature between incoming refrigerant and outgoing refrigerant, i.e., the greater the differential, the more complete the separation. The prior art includes a refrigerant reexpansion means for lowering the low side of the temperature range, but no means are provided for increasing the high side of the temperature range. Thus, a need is extant for such means.
Moreover, the art teaches activated carbon regeneration cells for the adsorption of contaminants from refrigerant just prior to purging of the contaminants into the atmosphere. As the regeneration cells operate over time, however, the capacity of the activated carbon therein to continue adsorption drops off as the carbon becomes saturated with refrigerant. The art teaches that a vacuum should be applied to the regeneration unit to physically knock the refrigerant off the activated carbon granules when said granules have become saturated. Once the refrigerants are knocked from the granules by the shock of the vacuum, they are then routed to the chiller. If the physical shock of the vacuum is inadequate to separate the refrigerants from the granules, the granules gradually become less and less effective and subsequent purges vent more and more refrigerant into the atmosphere
Instead of returning knocked-off refrigerant to the chiller, some systems burn off the refrigerant and release the combustion product to the atmosphere.
Thus, there is a need for an improved means for separating refrigerant from activated carbon granules in a regeneration cell.
However, in view of the prior art as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the needed improvements could be provided.